Buggy code:
public class Agenda extends Control { public Agenda ( ) { } private void construct ( ) { } @ Override protected String getUserAgentStylesheet ( ) { <START_BUG> return this . getClass ( ) . getResource ( ( ( "//jfxtras//internal//scene//control//skin//agenda//" + ( Agenda . class . getSimpleName ( ) ) ) + ".css" ) ) . toExternalForm ( ) ; <END_BUG> } @ Override public Skin < ? > createDefaultSkin ( ) { } public Agenda withId ( String value ) { } public ObservableList < Agenda . Appointment > appointments ( ) { } private final ObservableList < Agenda . Appointment > appointments = FXCollections . observableArrayList ( ) ; private void constructAppointments ( ) { } public ObservableList < Agenda . AppointmentGroup > appointmentGroups ( ) { } private final ObservableList < Agenda . AppointmentGroup > appointmentGroups = FXCollections . observableArrayList ( ) ; private void constructAppointmentGroups ( ) { } public ObjectProperty < Locale > localeProperty ( ) { } private final ObjectProperty < Locale > localeObjectProperty = new SimpleObjectProperty < Locale > ( this , "locale" , Locale . getDefault ( ) ) ; public Locale getLocale ( ) { } public void setLocale ( Locale value ) { } public Agenda withLocale ( Locale value ) { } @ Deprecated public ObjectProperty < Calendar > displayedCalendar ( ) { } private final ObjectProperty < Calendar > displayedCalendarObjectProperty = new SimpleObjectProperty < Calendar > ( this , "displayedCalendar" , Calendar . getInstance ( ) ) ; @ Deprecated public Calendar getDisplayedCalendar ( ) { } @ Deprecated public void setDisplayedCalendar ( Calendar value ) { } @ Deprecated public Agenda withDisplayedCalendar ( Calendar value ) { } public ObjectProperty < LocalDateTime > displayedLocalDateTime ( ) { } private final ObjectProperty < LocalDateTime > displayedLocalDateTimeObjectProperty = new SimpleObjectProperty < LocalDateTime > ( this , "displayedLocalDateTime" , LocalDateTime . now ( ) ) ; public LocalDateTime getDisplayedLocalDateTime ( ) { } public void setDisplayedLocalDateTime ( LocalDateTime value ) { } public Agenda withDisplayedLocalDateTime ( LocalDateTime value ) { } public ObservableList < Agenda . Appointment > selectedAppointments ( ) { } private final ObservableList < Agenda . Appointment > selectedAppointments = FXCollections . observableArrayList ( ) ; @ Deprecated public ObjectProperty < Callback < Agenda . CalendarRange , Void > > calendarRangeCallbackProperty ( ) { } @ Deprecated private final ObjectProperty < Callback < Agenda . CalendarRange , Void > > calendarRangeCallbackObjectProperty = new SimpleObjectProperty < Callback < Agenda . CalendarRange , Void > > ( this , "calendarRangeCallback" , null ) ; @ Deprecated public Callback < Agenda . CalendarRange , Void > getCalendarRangeCallback ( ) { } @ Deprecated public void setCalendarRangeCallback ( Callback < Agenda . CalendarRange , Void > value ) { } @ Deprecated public Agenda withCalendarRangeCallback ( Callback < Agenda . CalendarRange , Void > value ) { } public ObjectProperty < Callback < Agenda . LocalDateTimeRange , Void > > localDateTimeRangeCallbackProperty ( ) { } private final ObjectProperty < Callback < Agenda . LocalDateTimeRange , Void > > localDateTimeRangeCallbackObjectProperty = new SimpleObjectProperty < Callback < Agenda . LocalDateTimeRange , Void > > ( this , "localDateTimeRangeCallback" , null ) ; public Callback < Agenda . LocalDateTimeRange , Void > getLocalDateTimeRangeCallback ( ) { } public void setLocalDateTimeRangeCallback ( Callback < Agenda . LocalDateTimeRange , Void > value ) { } public Agenda withLocalDateTimeRangeCallback ( Callback < Agenda . LocalDateTimeRange , Void > value ) { } @ Deprecated public ObjectProperty < Callback < Agenda . CalendarRange , Agenda . Appointment > > createAppointmentCallbackProperty ( ) { } @ Deprecated private final ObjectProperty < Callback < Agenda . CalendarRange , Agenda . Appointment > > createAppointmentCallbackObjectProperty = new SimpleObjectProperty < Callback < Agenda . CalendarRange , Agenda . Appointment > > ( this , "createAppointmentCallback" , null ) ; @ Deprecated public Callback < Agenda . CalendarRange , Agenda . Appointment > getCreateAppointmentCallback ( ) { } @ Deprecated public void setCreateAppointmentCallback ( Callback < Agenda . CalendarRange , Agenda . Appointment > value ) { } @ Deprecated public Agenda withCreateAppointmentCallback ( Callback < Agenda . CalendarRange , Agenda . Appointment > value ) { } public ObjectProperty < Callback < Agenda . LocalDateTimeRange , Agenda . Appointment > > newAppointmentCallbackProperty ( ) { } private final ObjectProperty < Callback < Agenda . LocalDateTimeRange , Agenda . Appointment > > newAppointmentCallbackObjectProperty = new SimpleObjectProperty < Callback < Agenda . LocalDateTimeRange , Agenda . Appointment > > ( this , "newAppointmentCallback" , null ) ; public Callback < Agenda . LocalDateTimeRange , Agenda . Appointment > getNewAppointmentCallback ( ) { } public void setNewAppointmentCallback ( Callback < Agenda . LocalDateTimeRange , Agenda . Appointment > value ) { } public Agenda withNewAppointmentCallback ( Callback < Agenda . LocalDateTimeRange , Agenda . Appointment > value ) { } public ObjectProperty < Callback < Agenda . Appointment , Void > > editAppointmentCallbackProperty ( ) { } private final ObjectProperty < Callback < Agenda . Appointment , Void > > editAppointmentCallbackObjectProperty = new SimpleObjectProperty < Callback < Agenda . Appointment , Void > > ( this , "editAppointmentCallback" , null ) ; public Callback < Agenda . Appointment , Void > getEditAppointmentCallback ( ) { } public void setEditAppointmentCallback ( Callback < Agenda . Appointment , Void > value ) { } public Agenda withEditAppointmentCallback ( Callback < Agenda . Appointment , Void > value ) { } public ObjectProperty < Callback < Agenda . Appointment , Void > > actionCallbackProperty ( ) { } private final ObjectProperty < Callback < Agenda . Appointment , Void > > actionCallbackObjectProperty = new SimpleObjectProperty < Callback < Agenda . Appointment , Void > > ( this , "actionCallback" , null ) ; public Callback < Agenda . Appointment , Void > getActionCallback ( ) { } public void setActionCallback ( Callback < Agenda . Appointment , Void > value ) { }

Fix:
return Agenda . class . getResource ( ( ( "//jfxtras//internal//scene//control//skin//agenda//" + ( Agenda . class . getSimpleName ( ) ) ) + ".css" ) ) . toExternalForm ( ) ;